Zoom optical system, optical apparatus and method for manufacturing the zoom optical system

A zoom optical system comprising:

• a first negative lens group having a negative refractive power,
• a second negative lens group having a negative refractive power and disposed closer to an image than the first negative lens group, and
• an intermediate lens group disposed between the first negative lens group and the second negative lens group,
• wherein a distance between the first negative lens group and the intermediate lens group and a distance between the intermediate lens group and the second negative lens group change during zooming,
• the intermediate lens group consists of an object side subgroup having a positive refractive power and an image side subgroup having a positive refractive power disposed in order from an object,
• a lens component including a negative lens is disposed at a position closest to the object in the image side subgroup,
• the first negative lens group includes at least partly a vibration proof group movable so as to have a displacement component in a direction perpendicular to an optical axis,
• at least part of the second negative lens group is movable along the optical axis during focusing, and
• the following conditional expression is satisfied:
• 0.06
• <
• fa
• /
• fb
• <
• 1
• .
• 2
• ⁢
• 0
• where
• fa:
• a focal length of the object side subgroup, and
• fb:
• a focal length of the image side subgroup.

A method of manufacturing a zoom optical system, comprising:

• providing a first negative lens group having a negative refractive power;
• disposing a second negative lens group closer to an image than the first negative lens group;
• and
• disposing an intermediate lens group between the first negative lens group and the second negative lens group,
• the first negative lens group, the second negative lens group and the intermediate lens group being arranged in a lens barrel such that:
• a distance between the first negative lens group and the intermediate lens group and a distance between the intermediate lens group and the second negative lens group change during zooming,
• the intermediate lens group consists of an object side subgroup having a positive refractive power and an image side subgroup having a positive refractive power disposed in order from an object,
• a lens component including a negative lens is disposed at a position closest to the object in the image side subgroup,
• the first negative lens group includes at least partly a vibration proof group movable so as to have a displacement component in a direction perpendicular to an optical axis,
• at least part of the second negative lens group is movable along the optical axis during focusing, and
• the following conditional expression is satisfied:
• 0.06
• <
• fa
• /
• fb
• <
• 1
• .
• 2
• ⁢
• 0
• where
• fa:
• a focal length of the object side subgroup, and
• fb:
• a focal length of the image side subgroup.